Field of the Invention
The present invention relates to the field of streaming media and, in particular, to transition points in an image sequence.
Description of the Related Art
Streaming media often involves delivering some combination of audio, video, and text in a continuous manner from a content provider to a client media player via a communications channel. Examples of streaming media include video, audio, closed caption text, and movies that include video, audio, and closed caption text in a single media stream. The client media player presents the streaming media to an end-user via a suitable playback mechanism. In general, streaming media, such as a movie, is viewed at a target frame rate that is more or less constant, where the target frame rate is the number of image frames presented per unit of time, such as 60 frames per second. The streaming media is compressed and encoded so as to provide an acceptable image quality level at the desired frame rate, within the confines of the available bandwidth of the communications channel.
During playback of the streaming media, the bandwidth of the communications channel that is available for playback of the streaming media may vary dynamically. Such dynamic changes of available bandwidth may result from a various causes, including increases or decreases in the throughput of the communications channel, other demands on the communications channel, download requests or streaming media associated with other client media players, and the rendering demands and capability of the client media player. Generally, delivering streaming media at a constant frame rate with a variable quality level is considered preferable to delivering streaming media at a variable frame rate with a constant quality level. Accordingly, if the available bandwidth decreases, then the content provider may deliver streaming media at a higher compression level, corresponding to lower bandwidth consumption at a lower image quality level. If the available bandwidth increases, then the content provider may deliver streaming media at a lower compression level, corresponding to higher bandwidth consumption at a higher image quality level. The image quality level of the streaming media dynamically increases or decreases, responsive to dynamic changes in the available bandwidth of the communications channel.
One drawback with this approach is that changes in image quality level occur based on available bandwidth of the communication channel without regard to the quality or continuity of the viewing experience over time. For example, a change in image quality level could occur at a particularly noticeable point during a movie or during a particularly important scene, resulting in a compromised viewing experience for the end-user.